580 ex ii slave zoom control

Got a question and haven't been able to find the answer yet or I've overlooked it . I have 2 580exii's with one set to master and the other slave. I'm using both in manual mode so I'm controlling output. Let's say I've got the zoom set to 70mm on both flashes. It's easy enough to change the zoom setting on the master, but is there a way to control the zoom setting on the slave from the master?

Also, it seems my Sekonic L308s isn't measuring the 580's output anywhere near what the guide numbers show. It seems to work fine on my strobes. I put the Sekonic in flash mode, take a shot, and it reads about 2 stops under. It's bad enough that the test button on the flash fires at the same regardless of the power setting.

I suspect the flash meter is reading a pre exposure flash from your Canon Master / Slave setup, not the actual exposure flash.

Enjoy! Lon

FlashZebra wrote in post #13010325
I suspect the flash meter is reading a pre exposure flash from your Canon Master / Slave setup, not the actual exposure flash.

Enjoy! Lon

Thanks Lon, I hadn't thought of that. Sadly, I don't think that is it. I set only the on camera flash (no slave flash on) up for 2nd curtain sync and didn't get a preflash in manual mode which I've been using. It still metered about 1 1/2 stops under. I'll try later with my strobes to see how they do. I guess the Sekonic could be out of calibration?

D Thompson wrote in post #13011354
Thanks Lon, I hadn't thought of that. Sadly, I don't think that is it. I set only the on camera flash (no slave flash on) up for 2nd curtain sync and didn't get a preflash in manual mode which I've been using. It still metered about 1 1/2 stops under. I'll try later with my strobes to see how they do. I guess the Sekonic could be out of calibration?

Even if your on manual mode.. Assuming 1 on cam master and 1 slave....

here's wht I think your experiencing...

the Light meter is reading the Canon Wireless system pre-flash.

Even if your on manual mode on your master as long as the wireless system is turned on it will have preflash. ( Canon flashes don't have optical slave mode Su -4 for the nikon guys )
That preflash tells your slave to fire ( the slave can't understand that when it sees a flash it will fire. it only understands the Canon wireless system language that is sent through very fast multiple binary language of the canon wireless system to test this put your slave on manual as slave. then remove the other 580ex2 on cam removed it as master then press test button.. the slave would not respond.)


to avoid all the canon wireless system pre flashes.. just test your 1 580ex2 set on manual mode 1/1 ( removed on cam) and press the test button ( assuming you didn't set our test button as modelling light ).


tell us your results. hopefully I'm right.

aerosmith9110 wrote in post #13044179
tell us your results. hopefully I'm right.

You're right if you thought I was having cockpit trouble

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Still trying to figure out if the zoom setting of the slave can be set from the master. Any clues if possible?

D Thompson wrote in post #13045705
Still trying to figure out if the zoom setting of the slave can be set from the master. Any clues if possible?

no,
You must set it manually via the slave..

and if your on master mode ( wireless on ) when you press the test button an instruction is still sent put to slaves to also test fire... group A then Group b then group c.

aerosmith9110 wrote in post #13048216
no,
You must set it manually via the slave.

Thanks. Also just got a reply back this morning from Canon with the same answer.

Good to know that. Thanks.